1. Field of the Invention
The present invention relates to a thermal displacement correcting apparatus and a thermal displacement correcting method for a machine tool such as a NC lathe and a machining center.
2. Description of Related Art
The transfer of heat generated at power portions and slide portions and the like and a change in environment temperature cause thermal deformation in a machine tool. Because this thermal deformation affects the machining accuracy, an apparatus has been proposed that estimates the amount of thermal deformation from the machine body temperature and makes corrections when machining (for example, the apparatus described in Japanese Patent Application Publication No. JP-A-2006-281335). This thermal displacement correcting apparatus estimates and corrects thermal displacement between a workpiece and a blade edge using parameters such as position information, linear coefficient of expansion, and temperature and the like of a scale, a table, and the workpiece.
When this kind of thermal displacement correcting apparatus is applied to machines of the same model but with different specifications, the parameters must be prepared for each, which is tedious. That is, even with machines of the same model, if the machine specifications are different regarding the presence/absence or mounting position of a scale, or the way in which a table is mounted, the position information and linear coefficient of expansion and the like of the scale and table must be set for each set of specifications and stored in the thermal displacement correcting apparatus as a individual parameter files. As the number of sets of specifications increases, it becomes more tedious to set the parameters and operate the various parameter files, and the risk of a malfunction from an incorrectly set parameter increases, such that productivity and manageability of the thermal displacement correcting apparatus become poor.